1. Field of the Invention
The present invention relates to a transfer needle and, more specifically, to a transfer needle that enables safe, easy and reliable injection of liquid such as solvent or drug solution from its own container into a container with medicament contained therein, when dissolving the medicament in liquid such as solvent or drug solution and preparing drug solution for preparing fluid infusion and the like.
2. Description of the Related Art
Medicaments which are chemically unstable and may change their natures in a state of fluid infusion, such as antibiotics, anticancer agent, or blood preparation, are normally stored in a vial sealed with a rubber plug in a freeze-dried state, and then those medicaments are dissolved in a solvent such as distilled water, physiological salt solution, or glucose liquid and drug solution are prepared immediately before use.
In the most general method used for such dissolving and preparing procedure in the related art, a solvent is sucked out from a container containing the solvent by using a metallic hollow needle and a syringe and injected into a container with a medicament therein, and then the medicament is dissolved in the solvent to prepare a drug solution, and the prepared drug solution is returned to the syringe. However, this method is not only complicated, but also associated with a risk of accidental puncture by the metallic hollow needle. Therefore, various types of transfer needles which can perform dissolving and preparing procedure safely, easily and reliably are proposed (For example, JP56-9464B, JP54-16152B, JP49-47507B).
However, in the transfer needle in the related art, there are problems as described below. That is, the transfer needle is generally formed by injection molding, and thus there arise the following problems. For example, as shown in FIG. 38, a transfer needle 77 comprises a base plate 78, an upper hollow needle 79 projecting upward from the base plate 78, a lower hollow needle 80 projecting downward from the base plate 78 and communicating with the upper hollow needle 79, a skirt 81 provided so as to project upward from the outer peripheral edge of the base plate 78, a skirt 82 provided so as to provide downward from the outer peripheral edge of the base plate 78, and so on. When manufacturing the transfer needle 77 as described above by injection molding, for example, a method of using upper and lower metal molds 83, 84 as shown in FIG. 39, forming an insertion portion 84A to be inserted into an insertion hole 83A of the metal mold 83 on the metal mold 84, and molding the upper hollow needle 79 between the insertion hole 83A and the insertion portion 84A is conceivable.
However, in this method, the length L of the portion to be positioned inside the lower hollow needle 79 plus the insertion portion 84A of the metal mold 84 (this portion is supported to the metal mold 84 only at the lower end) is significantly long, and hence there arises a problem of strength. Therefore, the metal molds 83, 84 as shown in FIG. 40 are used for all practical purposes.
As described above, in the integral transfer needle in the related art, it is necessary to abut the small diameter liquid-specific hollow needle 79 and the medicament-specific hollow needle 80 against each other and mold them together. Therefore, when the metal molds 83, 84 are clamped too tight when molding, the metal molds 83, 84 may be broken. In contrast, when the metal molds 83, 84 are clamped with insufficient force, there arises such problem that flash may be generated at a portion 85 between the metal molds 83 and 84, and hence communication between the liquid-specific hollow needle 79 and the medicament-specific hollow needle 80 becomes defective. In this manner, in the related art, there was a problem in that adjustment a mold clamping force of the metal molds 83, 84 is difficult and hence molding of the transfer needle 77 cannot be performed easily.
In addition, the respective metal molds 83, 84 are formed with elongated ring-shaped holes 83B, 84B for forming hollow needles 79, 80 respectively in the vertical direction. In this case, when the diameters of the ring-shaped holes 83B, 84B are small, it is difficult to form these holes 83B, 84B, and it is further difficult to reduce the diameter of the insertion hole 83A and the insertion portion 84A, which requires a high level of technology. Therefore, when considering the molding stability of the transfer needle 77, the diameters of the ring-shaped holes 83B, 84B are obliged to be larger, and hence the diameters of the respective hollow needles 79, 80 increase correspondingly.
As shown in FIGS. 41(A) to (C), when the hollow needle 71 of the transfer needle is punctured into a rubber plug 72 of a vial 70, such phenomenon that the hollow needle 71 is pressed back by a resiliency of the rubber plug 72, that is, a kick-back phenomenon occurs. However, when the diameter of the hollow needle 71 is large, a force to be pressed back when the hollow needle 71 is punctured into the rubber plug 72 increases correspondingly, whereby the possibility that communication between the hollow needle 71 and the interior of the vial 70 is blocked or the hollow needle 71 comes off the rubber-plug 72 increases.
Also, as shown in FIGS. 37(A) to (C), when the metallic hollow needle 71 of the transfer needle is inserted into the rubber plug 72 of the vial, the cutting edge 73, which is formed like a pointed cutting edge, is punctured into the rubber plug 72 first and inserted into the rubber plug 72 as if it tears the rubber plug 72, and then the rear portion thereof is inserted in sequence into the rubber plug 72. In this case, since the rear (end) portion of the opening edge of the cutting edge 73 of the hollow needle 71, that is, a heel portion 74 is keen, a (coring) phenomenon that rubber material of the rubber plug 72 is cut off by the heel portion 74 tends to occur, whereby there was a possibility that small chips 75 of rubber are mixed into the prepared drug solution. Coring may also occur as in the case that the diameter of the metallic hollow needle 71 is large.
Furthermore, in the related art, when the drug solution is prepared in the vial by using the transfer needle, and then the prepared drug solution in the vial is transferred in turn to the syringe, it was necessary to pull the hollow needle of the transfer needle off the rubber plug of the vial, and then puncture the metallic hollow needle, which is connected to the syringe, again into the rubber plug to suck the prepared drug solution into the syringe. Therefore, there was a problem of generation of coring due to twice-puncture of the needle with respect to the rubber plug.
In order to solve this problem, such technology including the steps of inserting the respective hollow needles of the transfer needles into the rubber plug of the upper and lower vials respectively, mixing solvent and medicament in the both vials and preparing a drug solution, then when the empty upper vial is brought apart from the lower vial upward, bringing the distal (end) portion of the upper hollow needle or the like apart from the main body of the transfer needle, and dropping the distal (end) portion of the lower hollow needle as well in the lower vial, thereby taking the prepared drug solution out from the lower vial by the syringe through the main body of the transfer needle is proposed (for example, JP63-114649U). However, in this technology, since the distal ends or the like of the respective hollow needles remain in the respective vials, it is troublesome to dispose the distal (end) portions of the respective hollow needles and the respective vials separately, and in addition, the possibility to cause a needle-puncturing accident by the distal end portions of the respective hollow needles is high, and hence practical application was difficult.